Q.26. - Organic Chemistry

Question

Question: Draw all aromatic hydrocarbons that have molecular formula ${\mathit{C}}_{\mathbf{8}}{\mathit{H}}_{\mathbf{10}}$. For each compound, determine how many isomers of molecular formula ${\mathit{C}}_{\mathbf{8}}{\mathit{H}}_{\mathbf{9}}\mathit{B}\mathit{r}$ would be formed if one H atom on the benzene ring were replaced by a Br atom.

Step-by-Step Solution

Answer

Answer

Structural Isomers of  $C_8{H}_{10}$

2 stereoisomers

3 stereoisomers

3 stereoisomers

1 stereoisomer

Step 1: Benzene molecule

The benzene molecule is the simplest aromatic hydrocarbon or arene. It consists of six carbon atoms and has four degrees of unsaturation which makes it a highly unsaturated hydrocarbon. 

Unlike the other unsaturated hydrocarbons like akenes, alkynes, or dienes, the benzene molecule does not undergo the addition reactions. According to the Kekule model, the benzene molecule is a six-membered ring with alternating  bonds. But according to the current description, there is electron delocalization due to the orbital overlap in the benzene molecule.

Step 2: The isomers of the compound with the molecular formula C 8 H 10

Following is the structure of the aromatic hydrocarbons with the molecular formula $C_8{H}_{10}$:

Structural Isomers of  $C_8{H}_{10}$

 

The structure of the compounds after replacing the hydrogen atoms with bromine atoms from the above structural isomers is given below: 

2 stereoisomers

3 stereoisomers

3 stereoisomers

1 stereoisomer